dynamat question, and another one about a sub's sound

1) Is dynamat really necessary for cars that make vibration sounds on the outside? Isn't the vibration just a result of loose parts, and making everything tight should clear that up?

2) In my car, 2 12" xplods (I don't need to hear the "Sony sucks" comments). They're in a sealed box. For songs that play heavy lows, such as "What you know" by T.I., when it gets to the lowest note, the subs sound...hmm, I just want to say they bottom out of something. It sounds awful, it's hard to describe though. Maybe someone knows what I'm talking about here...what would cause that?

The subs are going to rattle crap throughout the car no matter how many times you tighten the bolt, dynomat just reduces the vibrations so keep things from rattling loose...as far as your subs "bottoming out", what type of amp do you have? Sounds like maybe you're not getting enough wattage to power them when they are demanding a high amount of wattage.

sony sucks

If it's a power problem, I can understand. I have dual profile hm700 (or something like that) that runs 200RMS@4ohms and 350@2ohms. The sonys are only svc and can only draw off 200 per amp, so it that would make sense (the sonys are 90-380w rms).

Thanks.

OMFG how many times do i need to post this on this forum

YOU DONT NEED FULL POWER TO A SUB TO MAKE IT HIT.

All you do is adjust the gains to compensate for the lower power levels, my current setup is running at half RMS they dont bottom out and they hit hard as hell. Ive done it in the past. You dont need to get a bigger amp for those sonys you will blow them with more than 250.

And the sound you are hearing is the sub clipping. Your gains are either set to high or to low adjust to fix the problem and o-scope can come in handy.

As for dynamat it is a dampener it is used to make sheet metal panels thivker to keep them from vibrating, so instead of the .125"thick sheet metal it becoms closer to 1/2 think. Its there to add a backbone to the metal.